Sorry to hear it wasn't as simple as a build up of temp files, and your Ram working overtime.

Please confirm you have the latest drivers installed here:
support.asus.com/download/download.aspx?install_nav=1&SLanguage=en-us

Also can you provide some more info on your system:

Windows OS and Service Pack?

Asus p6t exact model?

System Ram, and Hard Drive size? (it could even e a faulty Hard Drive)

Antivirus and or personal firewall being used?

If it happens with all sounds including Windows sounds?

After confirming the drivers from Asus (and also the exact model number)
Also run CheckDisk on your drive:
Start > Run > chkdsk /r > ok > Y > Enter > ok > Restart
Allow CheckDisk to run on next restart, and hopefully fix any issues.